ACGME (1998) Graduate medical education directory. Chicago, IL: American Medical Association. 462-496, 889-891.
ACGME (2006) Avaliable from http://www.acgme.org. Accessed January 28, 2006.
Hedges, L.V., Olkin, I. (1985) Statistical methods for meta-analysis. Orlando, FL: Academic Press.
Hedges, L.V. and Vevea, J.L. (1998) Fixed- and random-effects models in meta-analysis. Psychological Methods 3, 486-504.
Hunter, J.E. and Schmidt, F.L. (2004) Methods of meta-analysis: correcting
error and bias in research findings. Thousand Oaks, CA: Sage.